The 3GPP (3rd Generation Partnership Project) that is a standardization project of mobile communication systems is working on standardization of LTE Advanced that is an advanced version of LTE (Long Term Evolution) in 3GPP release-10 or later (see, for example, Non-Patent Document 1).
In LTE-Advanced, provision of a heterogeneous network is under study in which a low power base station (so-called pico base station or home base station) is installed in a coverage area of a high-power base station (so-called, a macro base station). The heterogeneous network can distribute a load of the high-power base station to the low-power base station.